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Add a synthetic missed optimization.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60186 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2008-11-27 22:12:22 +00:00
parent 895f085385
commit df563ca1f3
1 changed files with 24 additions and 0 deletions
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24
lib/Target/README.txt
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@ -984,3 +984,27 @@ define i1 @test(i8 %x) {
}
//===---------------------------------------------------------------------===//
These three functions all perform the same computation, but produce different
assembly. On x86, they are sorted from slowest to fastest.
define i8 @udiv(i8 %x) readnone nounwind {
%A = udiv i8 %x, 250
ret i8 %A
}
define i8 @select(i8 %x) readnone nounwind {
%A = icmp ult i8 %x, 250
%B = select i1 %A, i8 0, i8 1
ret i8 %B
}
define i8 @addshr(i8 %x) readnone nounwind {
%A = zext i8 %x to i9
%B = add i9 %A, 6 ;; 256 - 250 == 6
%C = lshr i9 %B, 8
%D = trunc i9 %C to i8
ret i8 %D
}
//===---------------------------------------------------------------------===//